Oil recharging and recovery method and apparatus



arch 29, 1932. RANNEY 1,851,446

OIL RECHARGING AND RECOVERY METHOD AND APPARATUS Filed Feb. 1, 1929 3Sheets-Sheet 1 33% M S ated/mug March 29, 1932. RANNEY 1,851,446

OIL RECHARGING AND RECOVERY METHOD AND APPARATUS Filed Feb. 1, 1929 3Sheets-Sheet 2 o o O O- 9 0 o o o o o 0 o o o 0 O O o o 0 avwembozWMQMMWWH March 29, 1932. RANNEY 1,851,446

OIL RECHARGING AND RECOVERY METHOD AND APPARATUS Filed Feb. 1, 1929 3Sheets-Sheet (5 j gvwemtoz Patented Mar. 29, 1932 UNITED STATES PATENT.orator:

LEO BANNEY, 01 NEW YORK, N. Y ASSIGNOR TO STANDARD OIL DEVELOPMENT COM-PANY, A CORPORATION OF DELAWARE OIL BECHABGIN'G AND RECOVERY METHOD ANDAPPARATUS Application filed February 1, 1929. Serial No. 336,857.

invention is to recharge the oil with gas, thereby enlivening the oil orincreasing its tendency to flow. In the method described herein gas isnot primarily caused to form a moving barrier which drives oil beforeit. On the.

contrary, the oil is directly modified by the gas so that flow withoutapplied pressure is ossible. This application is a continuation 1n partof my co-pending applications Serial No. 127,233, filed August 6, 1926,and Serial N 0. 160,793, filed January 13, 1927.

The invention will be fully understood from the following description,read in connection with the accompanyingdrawings, in which Fig. 1 is adiagrammatic vertical section showing a portion of a mine gallery andillustrating the first stage of the recharging operation;

Fig. 2 is a similar view showing the second stage of that operation;

Fig. 3 is a similar view showing the oil collecting stage Fig. 4 is adiagrammatic plan showing a preferred arrangement of the mine galleries;

Fig. 5 is a vertical section through a control valve arranged in a minewell; and

Fig. 6 is a similar view showing an alternative form of valve.

Referring first to Figs. 1 to 4 of the drawings, 1 denotes amine gallerydriven in a lower can rock 2 underlying an oil sand 3. which containsshale partings 4. or the like. An upper cap rock 5 covers the oil san'd.Conduits 6 and 6' are set in holes 7, drilled upwardly into the lowercan rock, but preferably not through into the oil sand. The holes may bedrilled vertically as shown. or at an angle. The lower part of eachholeis enlarged to receive a sealing material 8. (cement, lead wool, orthe like) which makes a fluid-tight seal between the can rock 2 and the'conduits 6, 6'. Openings 9. drilled through the conduits as extensionsof holes 7, tap the oil sand and form what I term mine wells. Openings 9are preferably enlarged at their ends by reaming or blasting to formfluid distributing or collecting areas 10.

Conduits 6 are connected to a pipe 11 which is in turn connected to asource of gas or air under pressure, and conduits 6 are connected to anoil collecting pipe line 12. Control valves 13, preferably of the gatetype, are installed in each conduit.

While the described method of tapping the oil sand is preferred, it willbe .understood that any method may be adopted which permits gas underpressure to be injected into the sand at or near the bottom. Instead ofworking from below as illustrated, it is evident that an equivalentresult may be obtained by drilling from above, provided of course thatthe opening through the sand is cased or cemented so that gas cannotescape into the sand except near its bottom.

For best results the mine gallery should be formed about the margin ofthe tract to be worked, for example as shown in Fig. 4, which representsa square 40 acre tract encompassed by a gallery from which numerous minewells 9 are drilled into the sand.

In the preferred operation of my method, a gas under pressure is passedinto the oil sand through conduits 6. I prefer natural gas for thispurpose, though air, mixtures of air and natural gas, etc., may be used.In the first stage of he recharging operation, as illustrated in Fig. 1,the pressure is kept relatively low (10 to 50 lbs. per square inch forsands of average porosity). This is to insure the formation of a gaslayer throughout the bottom area of the sand.

If high pressure is initially applied, there is a tendency for the gasto break through,

as between the shale partings 4, and spread Y throughout the upperregion of the sand, leaving the lower part untouched. Gas tends to passlaterally more readily than vertically through the oil sand, and if theinitial pres sure is not too high, a good distribution of gas can beobtained throughout the whole lower area.

When this has been accomplished the pressure is increased, say to aboutto 150 lbs. per square inch. The gas enters the charged lower layer andascends through the sand.

This condition is illustrated in Fig. 2. During the rechar ing operationthe gas moves outwardl an upwardly from the intake wells and gradually.rises toward the to of the sand. In so doing it charges the 011 withgas.

I do not wishto be limited to the particular pressures specified, asthese will naturally vary in accordance with porosity of the sand, theinitial gas content of the oil, and other conditions. The pressure inthe preliminary charging stage will ordinarily be within the range of 10to 50 lbs. per square inch and for the second sta e between 50 and 300lbs. per square inch. Iore than two stages of pressure may, of course,be applied where conditions necessitate pressure increase.

In some cases it is desirable to remove a portion of the oil from thebottom layers of sand before entering the stage of hi her pressure, thepurpose being to make the bottom layers 0 sand more permeable to the gasduring the second stage. This partial extraction of oil from the sandbottom is accomplished by removing the applied pressure and allowing theoccluded gas in the bottom oil to expand and drive the oil to thenearest producing well. Once the bottom layers of sand are partiallycleared of oil, the gas, when a ain applied under pressure, spreads rapiy throughout the sand bottom The time required for recharging will varygreatly. In porous sands, for example, distributlon of gas throughoutthe lower area may be obtained by holding pressure on a 40 acre tractfor three or four weeks. A similar period will be required for chargingthe upper areas at higher pressure. In tight sands much" longerapplication of pressure is required. The gas may be heated and inspecial cases unexcavated drainage tunne1s may be formed, as describedin my applications referred to above.

During the recharging period all of the oil outlets are preferablyclosed. When the oil in the sand has been recharged substantiallythroughout, the gas is shut oil and the oil collecting conduits 6' areopened to permit flow of oil into line 12. If desired the gas line 11may also be utilized for the collection of oil. Suitable pumps,separators, etc., are provided for forwarding the oil and gas to theearths surface, for example as shown in m' In some cases it ispermissible to withdraw oil during the recharging stage. In general,however, I prefer to complete this stage before any oil is withdrawn. Inthe present method I do not, in any case, use the initial charging gasas a moving barrier to expel oil. Although it is not generallynecessary, I may aid in theexpulsion of the charged oil by more gradualapplying fluid pressure (water, gas, etc.) or by applying suction.

Recovery of oil through mine wells as described isnormally mostconvenient, but other means are also suitable, For instance, in manyfields which are no longer producing oil. because of gas depletion,there are aba'n doned surface wells-which can be used for oil recoveafter the oil has been enlivened as described. When recovery of oil isthrough mine wells, the valves therein may be operated to control flowof oil so as to prevent too great an escape ofgas through oil collectingoutlets, or to prevent other undesirable results. When mine-wells areproducin oil it is sometimes desirable to keep an oil sea above thevalve to retain free gas, but at other times it is desirable to allowthe gas to flow freely-at various intervals to create a diflerential'ofpressure within. the sand, the lowest pressure being at the producingwell. This sudden release of pressure enables the occluded gas to expandand to push the oil to the producing well. The periodic venting may beby manual operation ofvalves, or pressure responsivedevices, floatcontrolled valves, or the like, may be used to vent gas automaticallywhen required. In Fig. 5 a pressure responsive valve is illustrated.This comprises a valve head 13 and a valve seat 14 in the form of anannulus mounted in the pipe 15. A centrally erforated plate 16 isadjustably arranged elow the valve seat in the pipe. A coil spring 17 issecured to the valve head and encircles a valve stem 18 which plate 16.The spring is supported by the latter plate, which may be adjusted toregulate the tension on the spring so as to cause the valve to open atthe desired pressure. After the pressure is relieved, the valve closes.Fig. 6 shows a float operated valve. comprises a'valve head 19 and avalve seat 20. The orifice in this should be beveled downwardly toprevent sand grains from collecting and keeping the valve open. A float21 is attached to a stem 22 secured to'the valve head, preferably byadjustable means. When the level of oil in the mine well reaches apredetermined level, the valve opens to permit. temporary outflow intothe collecting line 12. c

The valves in the gas injection conduits 6 may be selectively regulatedto control the Y'tdt' f .Ith' th d't'- U. S. Patent 1,660,818, grantedFebruary 28, m m uc Ion 0 gas 18 way 8 1s m 1928.

may be obtained by test devices such as are shown in my United StatesPatent 'No. 1,667,269, granted April 24, 1928.

y invention is to be distinguished from prior methods in which gas isforced into an runs through seat 14 and oil sand without insuring thatit shall enterm less resistance to the entry of the gas.

at the bottom. If the gas has free access to the upper portion of thesand, it will preferentially fill that portion of it, since the upperpart is relatively oil-free and therefore Ofi'Flll'S e barrier of gasthus formed above the oil can be used to force it out to a substantialextent, but will not serve effectively to recharge the oil with gas. Thelatter result is obtained by the present method. Oil properly rechargedwith gas flows freely and can be readily withdrawn from the sand,irrespective of applied pressure, which in some cases is ineffective dueto interposed shale barriers or other obstructions in the sand.Recharged oil contains its own expulsive agent (occluded gas) and thisbecomes operative whenever the pressure is released, even in part.

The methods described above are preferred, but it will be understoodthat various changes and alternative procedures may be adopted withinthe scope of the appended claims in which it is my intention to claimall novelty inherent in the invention as broadly as the prior artpermits.

I claim:

1. Method of recovering oil from an oil bearing stratum, comprisingpassing gas into the stratum from near the bottom only and below thelevel of oil in the stratum, and withdrawing oil charged with gas.

2. Method of recovering oil from an oilbearing stratum, comprisingpassing gas at relatively low pressure into the stratum from near thebottom only and below the level of oil in the stratum, selectivelyregulating the introduction of the gas, and withdrawing oil charged withgas.

3. Method of recovering oil from an oilbearing stratum, comprisingintroducing gas first under relatively low pressure and then underhigher pressure into the stratum from near the bottom only and below thelevel of oil in the stratum, and withdrawing oil charged with gas.

r 4. Method of recovering oil from an oilbearing stratum, comprisingintroducing gas under relatively low pressure into the stratum from nearthe bottom only and below the level of oil in the stratum, until thelower area of the stratum is substantially filled wlth gas, thenintroducing gas under a higher pressure so as to cause the upper portionof the stratum to be substantially filled with gas, and withdrawing oilcharged with gas from the stratum.

5. Method of recovering oil from an oilbearing stratum, comprisingpassing gas at relatively low pressure into the stratum from near thebottom only and below the level of oil in the stratum, then injectinggas at a.

higher pressure from below the level of oil in the stratum, selectivelyregulating the introduction of the gas, and withdrawing oil cl chargedwith gas.

6. Method of recovering oil from an oil sand in which the oil isrelatively free of gas, comprising introducing gas into the sand belowthe level of oil from about the margin of the tract to be worked untiloil in the sand is substantially charged with it, and thereafter openingoil outlets so that the oil charged with gas may flow from the sand.

7. Method of recharging oil within the pores of an oil sand in a naturalearth stratum, comprising the introduction of gas under pressure at apoint near the bottom of the sand and below the level of oil in thesand, so that the gas moving outwardly and upwardly from the intake maygradually rise toward the top of the sand, recharging the oil in itspath.

8. Method of recharging oil within an oil sand, comprising theintroduction of gas under relatively low pressure near the bottom of thesand and below the level of oil in the sand, withdrawing the oil socharged, and filling such partially drained area with gas under higherpressure for movement outwardly and upwardly through the remainder ofthe sand body.

9. In an installation for working an oil sand from a mine gallerylocated adjacent the sand but spaced therefrom, the improvement whichcomprises gas inlets opening near the bottom only of the sand, means forpassing gas through the openings to recharge the oil with gas, and meansfor withdrawing oil.

10. The method of charging oil in a tract of natural earth stratum withgas, which comprises injecting the gas into the stratum below the levelof the oil in the stratum from the outer horizontal edges of the tract.

11. The method of charging oil in a natural earth stratum with gas,which comprises injecting the gas into the stratum below the level ofthe oil in the stratum under progressively increasing pressures to causethe gas to flow laterally into the oil impregnated stratum and upwardlythrough the oil carrying portion of the stratum.

12. The method of charging oil in natural earth stratum with gas, whichcomprises injecting the gas into the stratum below the level of the. oilin the stratum at slightly greater than atmospheric pressures to causethe gas to flow laterally through the stratum, and elevating thepressure of the gas whereby the gas flows upwardly through the stratum.

' LEO RANNEY.

